Important objects can be highlighted in a picture by blurring the background, cutting out the subject, removing the color from unimportant areas, or adding color to important features. An example of the last variation is Schindler’s List [1], filmed by Steven Spielberg entirely in black and white, except for one scene showing a child wearing a bright red coat in the otherwise monochrome shot. A similar technique was used in the film Pleasantville [2] by removing color, then adding it back in selectively.

In many cases, whole series of digital images need the same kind of modifications, which forces the photo-grapher to repeat the same steps time and time again in GIMP. Have you ever considered retouching in Perl?